Manufacture of imitation pearls



Dec- 16, l952 A. J. J. POELMAN MANUFCTURE OF IMITATION PEARLS 5 Sheets-Sheet l Filed June 7, 1948 4 .FG.7. C?

@f2/g MW Dec. 16, 1952 A J, POELMAN 2,622,042

MANUFCTURE OF' IMITATION PEARLS Filed June 7, 1948 3 Sheets-Sheet 2 :if a Mz.

Dec. 16, 1952 A. J, J, POELMAN 2,622,042

MANUFACTURE OF IMITATION PEARLS Filed JunQ 7, 1948 3 Sheets-Sheet 3 f a f/.9 l I Vaga,

DOOOC Patented Dec. 16, 1952 MANUFACTUR'E 0F IMITATION PEARLS Armand Jacques Julien Poelman, Paris, France Application J une "4', 1948, Serial No. 31,573 In France June 10, 1947 7 Claims.

Imitation pearls are generally formed by cores of a translucent material around which there 'is applied a varnish sometimes described as "es sence dorient in lorder -to impart to said core a nacreous lustre approaching that of natural pearls.

Similar means are also used to manufacture other types of beads, simulating turquoise or coral for instance, varnish compositions of appropriate colour being used.

The present invention more particularly relates to the step of `varnish application or coating step in a process of the above-dened character.

As a rule, to accomplish that step, the pearl or bead cores are mounted on rods engaging a hole formed therein, or alternatively, if said cores are formed with a through aperture, they are threaded at spaced intervals on rods or wires. They are thereafter dipped in a varnish bath or subjected to a jet of varnish from an aerograph pencil vor airbrush. The beads have then to be removed from their supporting means Aor stripped from the supporting 4rods or Wires, and nally it is necessary to remove the annular burrs of solidified varnish formed around both opposite openings of the hole in the bead.

All of these operations require a considerable number of hand operational steps. Moreover if .an air-brush is used there is considerable loss of varnish, which is particularly appreciable Aespecially in the case of essence dorient base varnish, which is an expensive material.

It is an important object of my invention to improve the varnish-coating operation of beads lof the type described, so as to achieve a substantial saving both as to labor and the amount yof varnish composition used.

Specifically, itis my object to provide a method yof applying a coat of varnish to imitation pearls and the like, which comprises placing the pearl cores .on a surface, applying varnish to said cores throughout the entire area thereof except in a small Zone surrounding the point of contact of each said core with said surface, and varying said points of contact in all of said cores during the coating operation.

In a preferred embodiment, the cores are rst coated as far as a point a small distance away from their point of contact with a supporting sur-face, then the cores are made to contact a supporting surface at a point diametrically oppgsite rsaid first-mentioned point of contact so i@ @MQW them to be .Coated thrcushout the remainder of their surface area..

Where the application of varnish is .eiected by means of an air-brush, the pearl cores are preferably spread over the supporting surface with a spacing between the individual cores such that the jet delivered by the air-brush will be substantially tangential to both any .given core and to the adjacent cores. This feature -is effective to minimize the delivery of superfluous -cr excess varnish onto the supporting surface.

Alternatively a dipping process may be used. Preferably the bead cores are then caused to adhere to the under surface of a support over a bath of varnish composition and the surface level of said bath is varied so as to coat the peripheral surface of said cores up to a predetermined distance from their point .of contact with said supporting surface. Then the .cores are transferred to the under surface of a support to which they are made to adhere at a point diametrically opposite to said rst point of contact, and the level of the varnish is again controlled similarly as in the previously-described phase of the coating operation.

The accompanying drawings illustrate -by way of example lsome practical forms of embodiment of the method of the invention vand means used in carrying it into effect.

Figs. 1 to 12 relate to a coating process involving the use of an air-brush.

Figs. 1 and 2 are explanatory diagrams each illustrating in elevation, respective stages .of the coating procedure of a bead-core assumed to be treated individually.

Fig. 3 is a .corresponding plan view.

Fig. 4 is a view similar to Fig. 1 illustrating the spacing-pattern used in spreading the beadcores when treated simultaneously.

Fig. 5 shows a first means for varying the point of engagement of the cores With the support surface thereof after the iirst coating Astep has been completed.

Figs. 6 and 7 respectively relate to two other means used for the same purpose.

Fig. 8 is an entirely diagrammatical View in plan of a machine according to the invention for mass production operation.

Fig. 9 illustrates a modification for use with an air-brush.

Fig. 10 is a longitudinal sectional View of another form of a highoutput machine for use in a coating process employing an adhesive supporting sheet,

Fig, 11 is a corresponding plan View.

Fig. 12 shows one form of device which may be used for over turning the cores in connection with the machine shown in Figs. l and 1l.

Figs. 13 and 14 relate to a dip-coating procedure.

Fig. 13 is an explanatory diagram.

Fig. 14 is a diagrammatical cross section on an axial plane, of a device for carrying into practice a dip-coating process according to the invention, and

Fig. 15 illustrates an accessory means usable in connection with any of the embodiments of the invention.

As shown in Figs. l and 2, the reference I designates the core of the artificial pearl or bead, which is assumed to be substantially spherical in form, 2 is the supporting surface which in that assumption will be at. The core may be positively positioned on said surface through any suitable means some of which will be described by way of example hereinafter. The jet issuing from an air-brush fed'with a supply of varnish is directed onto the core. As shown the jet is directed at an angle of 45 with respect to the plane of the supporting surface. The vertical plane containing said jet is then rotated around the core so as to assume the successive positions shown A, B, C, D in Figs. 1 and 3. On completion of this first coating stage the bead is thus coated with varnish except in the area surrounding its point of contact with the supporting surface 2. This area is a portion of a sphere dened by a cone having its apex at the center O of the core and a cone angle of 90. The coat of varnish is thicker at the upper portion of the core, which has been continuously receiving the jet from the air-brush, than in the lower portions which have only been impinged by said jet throughout part of the duration of the operation.

For the second step of the coating operation the core I is caused to engage the supporting surface 2 at a point diametrically opposed from the point through which it engaged said surface in the initial step. The core is thus made to present to the air-brush jet its as yet uncoated portion, surrounded by those portions which had been less fully coated in the first coating step. The second coating step is effected exactly in the same manner as the above-described rst step. On completion of the second step the bead is covered with a substantially uniform coat of varnish. It thus is entirely coated without it being possible for the previously-indicated defects -to occur, as found in beads coated on supporting rods or wires. It Will of course be understood that the twostage coating operation of the invention or each of the consecutive steps thereof, can be repeated as many times as may be necessary or desirable.

In practice, a large plurality of bead or pearl cores are coated simultaneously. For that purpose the cores are spread over a common supporting surface 2, the mutual spacing between the individual cores being so predetermined that the jet from the air-brush will be tangential to both any given core and to the immediately adjacent ones. This feature is illustrated in Fig. 4, in which the direction of the air-brush jet is shown inclined at an angle of 45 with respect to the supporting surface 2. In that case the mutual spacing between adjacent core-centers in any direction is equal to the length of the diagonal of a square whose sides are each equal to the diameter of a core. Under such conditions the spraying of superfluous varnish onto the Support ing surface 2 Will be minimized.

In turning the cores upside down after the first coating stage has been completed various means may be used.

As shown in Fig. 5 use is made for that purpose of the indentated or perforate plates conventionally used in picking up cores from the containers in which they are stored in loosely packed condition. Said plates are dipped into the mass of bead cores and then Withdrawn, whereupon they are adapted to retain a core in each of the identation or perforations therein. After the cores thus retained on the perforate plate have been subjected to a first coating step, a second and identical perforate plate 4 is superimposed over them in such a way that the holes in said second plate will each register with one of the beads. The entire assembly is then bodily reversed and the first strip, which now is on top, is removed.

As shown in Fig. 6, the bead cores after being positioned on a perforate plate 4, are then covered with a strip of adhesive-coated material 5 and slight downward pressure is applied to the assembly through the interposal of a strip e of suitable material such as a somewhat iirm sheet rubber composition. The beads are thus made to adhere to the adhesive strip and the adhesive strip is then withdrawn together with the beads adhering thereto and the beads are in that condition subjected to the rst coating step. In order to reverse them for the second coating step a further sheet or strip of adhesive-coated material is placed over the beads and downward pressure is exerted on the assembly through an interposed strip of highly flexible rubber, such as spongeor cellular rubber for instance. The adhesive sheet is thus caused to adhesively engage a larger peripheral area of each bead than in the first similar operation. It follows that on removal of the second adhesive-coated strip the bead cores are adapted to remain in adhering engagement with the latter while being stripped oif the rst adhesive sheet. They are then ready to be subjected to the second coating step.

Alternatively I may use a second adhesive sheet which is inherently more highly adhesive in character than the first adhesive sheet used, or as a further alternative one end of the adhesive strip to be removed may be folded back towards its opposite end so as to dene a very acute angle With its initial direction, and then a pull may be exerted on the folded end towards said other end.

Now turning to Fig. 7, the perforate plates l form one of the sides of a flat box l provided with a tubular connection adapted to be connected with a source of vacuum. The bead cores may thus be retained in place under the action of atmospheric pressure. To accomplish the overturning step it is only necessary to lay a second identical perforate plate over the beads, said second plate also forming part of a similar vacuumbox, and apply vacuum to said second box, while at the same time placing the rst said box relating tothe plate 4 in communication with atmosphere. The beads will then be retained on said second perforate plate, and may be subjected While retained thereon to the second coating step.

As shown in Fig. 9 the bead cores are supported in a plate 4 formed with holes large enough to allow a substantial portion of the spherical contour of each individual bead to project thereunder so as to engage a surface which may be that of a rubber band I4 or the like, the band I4 being subjected to a continuous or intermittent longitudinal feed motion together,

preferably, with a transverse motion. The point of contact `of the pearl cores with the supporting surface is thus continuously and periodically varied, so that at the end of a predetermined period of time the entire surface thereof will be uniformly coated with varnish.

In large-scale air-brush coating operation according to the invention, a machine may be used of the type shown by way of example in Fig. 8, which is a diagrammatic plan View. The machine shown comprises a table of generally elongated annular form, on which a number of plates 4 retaining the cores to be coated are supported. A pair of carriages E are adapted to feed along or around said table at a constant spacing from each other, the feed movement being continuous or intermittent and produced through any suitable means. Each of said carriages supports at the forward end thereof four sets of air-brushes or aerograph pencils Iii, said sets being arranged in two-by-two opposed relationship along the longitudinal and transverse side edges of said carriages respectively. The jets from said air-brushes are directed at a common predetermined angle to the plane of the table 9. The carriages E rearwardly mount a drying device II, such as an infra-red drier.

The bead cores are thus subjected to a coating step followed by a drying step as each of the carriages E' is fed past them. Said steps may be repeated as many times as may be necessary or desirable, the cores being reversed only on completion of a predetermined number of successive passes of the carriages The airbrushes on said carriages are thus caused Yto act in succession, and optionally several times running upon the cores, for each given position of the latter. The cores may also be overturned after a carriage is passed thereover, or after each time a carriage is passed thereover, so as to cause the two successive coating steps to alternate.

In the machine shown in Figs. l0 to 12 inclusive, the pearl cores are uniformly fed under and past an air-brush mounted at a fixed station.

The cores are placed on an endless conveyor belt comprising an adhesive tape I9 trained over and around a pair of parallel rolls ZIB- 2| one at least of which is power-driven. The airbrush 22 is so mounted that its jet is inclined at 45 to a horizontal plane, said air-brush being supported at one end of an arm pivotally mounted on a fixed upright shaft XY. The air-brush is periodically swung around the axis of said shaft so as to alter the angular orientation of its jet I with respect to the cores to be coated.

The pearl cores issuing from under the airbrush are fed by the adhesive tape I9 and the coat of varnish just applied to them is adapted to dry or cure prior to the point where the cores are brought back to a position underlying the air-brush. The cure may be accelerated through the use of an array of infra-red lamps 3d arranged above the adhesive tape carrying the newly-coated cores. After the bead-cores have been subjected to the first coating step, they are overturned in readiness for the second coating step, this being accomplished by picking up the cores with another adhesive tape to strip them off the nrst adhesive tape (see Fig. 12). tape I9 carrying the partially coated beads and the newly applied adhesive tape 23 are fed together into and through the nip of a pair of oppositely rotated rolls 24 and 25. The roll 25 engaging the sec-ond or empty adhesive tape 23 The' is provided with a substantially soft or yielding lining 26. Both adhesive tapes are driven .at a common rate of feed from the leading rolls 21- 28 driven in turn from a common drive shaft 29 as for example through sprocket chains 30- SI or the like. The rolls 21--28 are operatively connected with the rolls 24-25 e. g. through further sprocket chainsy 32 to drive said lastmentioned rolls.

The contact area between the bead cores .and the empty adhesive tape 23 is larger than that between said cores and the tape I9 because of the presence of the soft lining 26 on the roll 25. It follows that the cores will adhere to said empty tape through the uncoated portions of their surfaces. The empty or second tape is mounted on the machine as shown in Figs. 10 and 1l where the beads are shown being subjected to the second coating step. On completion thereof the nished beads or pearls are stripped off the adhesive tape by means lof a doctor blade or the like.

The improved method of my invention is also applicable in connection with a coating procedure in which the cores are dipped rather than subjected to an air-brush jet, such dipping procedure generally being more advantageous where large-size beads are concerned.

In such case, according to the invention, the cores I may be made to adhere to the under face of a supporting surface 2. They are then immersed in a mass of varnish composition, for instance up to the level indicated at aa in Fig. 13 i. e. up to a distance from their point of contact with said surface sufcient to prevent the varnish from rising thereto through surfacetension effect. The cores are then withdrawn from out of the Varnish and dried. This first coating step may be repeated as many times as may be desired. The cores are then reversed for example through the use of any one of the means described above in connection with Figs. 5 to 7, then subjected to the second coating step in their reversed condition.

In practice it may be found desirable that each coating step be in turn subdivided into more than one stage, that is, rather than immediately immersing the cores up to the level ad in the varnish, they may be successively immersed as far as various intermediate levels ee-dd-cc-bb, a drying operation being effected between each successive pair of such partial coating stages.

In carrying out the dip-coating process according to my invention, matters may be so arranged that the surface 2 to which the cores adhere will constitute the ceiling of a sealed chamber I2 (see Fig. 14) containing a suitable gaseous atmosphere above the varnish bath I3. This chamber is made to communicate at its base with another Varnish container I9 provided with means such as a piston I5 operative to exert pressure on the varnish therein. Under such circumstances, there is the assurance that the varnish will at no time rise within the chamber I2 high enough to contact the surface 2. As the pressure exerted on the varnish at I9 is increased the varnish will rise at I2, compressing to a corresponding degree the gaseous atmosphere overlying the varnish. It is thus possible through the application of predetermined pressure values tc bring the varnish level to the various vertical positions ee-ddcc-bb-aa. The top I6 of the chamber I2 is provided with a pressure-gauge I1 making it possible to control the pressure prevailing in the space above the varnish in the chamber I2. Said top portion is Vremovable to .allow insertion and removal of the core-retaining surfaces thereinto and therefrom.

When the pearl cores to be coated are perforated ones, it is desirable that the end or one end of the perforation therein be arranged at the point of contact of the core with the supporting surface. It is only necessary for that purpose see Fig. to place the surface 2 retaining the cores upon a table I8 which is subjected to a quick vibratory movement of small amplitude, particularly in a longitudinal direction, the vibrations being imparted to it through any well-known means such as an electromagnetic or pneumatic or any other suitable type vibrator. Then the cores in which the perforations were not initially directed normally to the supporting surface assume a spinning motion, which will cease as the end or one end of the perforations therein reaches a position contacting said surface, because the ends of said perforations behave more or less as a flat formed on the spherical surface of the core.

In case the perforations in the bead cores are relatively large in diameter, the presence of said flat which then involves an excessively large area 'of the external surface of the coreV would become troublesome in accomplishing the coating operation according to the invention. It then would be preferable to bring the center axis of said perforations to a predetermined inclination, uniform in all of the cores, with respect to the supporting surface.

For that purpose, after first having caused the cores to assume a. position in which the axes of their perforations are oriented normally to the plane of the adhesiveY supporting tape, this being accomplished through imparting a vibratory motion thereto as described above, the cores may then be picked up by means of another adhesive tape which is caused to engage each core at the desired angle, for instance through the use of a device similar to the one shown in Fig. 12. It Will of course be understood that the method of the invention may be carried out with greater simplicity in the coating of solid or non-perforate bead cores.

It is to be understood moreover that the invention is by no means restricted to the specific procedure and means illustrated and described and that modifications may be made therein within the scope of the ensuing claims.

What I claim is:

1. A method of coating the cores of imitation pearls and the like which comprises placing said cores on an identated plate, applying to the tops of said cores an adhesive sheet material applying slight pressure to said sheet material to cause said cores lightly to adhere thereto, coating said cores as far as a predetermined small area surrounding the points of contact of said cores with said adhesive sheet, applying another adhesive sheet to said cores in diametrically opposed relationship with said first adhesive sheet, applying a relatively stronger pressure to said second adhesive sheet than saidpressure previously applied to said rst adhesive sheet, stripping said second adhesive sheet with said cores attached thereto from said rst adhesive sheet and coating said cores as far as a predetermined small area surrounding the points of contact of said cores with F said second adhesive sheet.

2. A method as in claim 1 wherein pressure is applied to said first adhesive sheet through the interposal of a relatively unyielding sheet rubber element, and the pressure on said second adhesive sheet is applied through the interposal of a relatively yielding sheet rubber element.

3. A method as in claim 1 wherein said second adhesive sheet has a stronger adhesive characteristio than said rst sheet.

4. A method of coating the perforated cores of imitation pearls and the like which comprises placing said perforated cores onto an adhesive sheet with one end of the perforations in said cores engaging said surface, coating said cores as far as a small area, surrounding said one end of said perforations therein, then placing said cores onto another adhesive sheet with the opposite end of said perforations engaging said other surface, and coating said cores as far as a predetermined small area surrounding said other end of said perforations.

5. A method as in claim 4 wherein said perforated cores are placed on an adhesive sheet to which vibratory movements are adapted to be imparted and imparting vibratory movements of small amplitude to said surface whereby said cores are adapted to engage said surface through one end of the perforations therein.

6. A method for coating the cores of imitation pearls or the like, which comprises fixing a plurality of said cores in uniformly spaced condition on an adhesive surface which contacts each of them substantially on a point, spraying a coating composition on said cores in a direction sub` stantially tangential to adjacent cores, then transferring the whole of said cores to another adhesive surface which contacts each of them on a point diametrically opposed to their initial point of contact, and again spraying the coating composition on said cores in the same direction as before.

'7. A method for coating the cores of imitation pearls or the like, which comprises maintaining said cores in contact substantially by a point with an adhesive sheet, applying a coating composition on said cores with exception of a zone about their point of contact with said adhesive sheet, then causing the cores to contact an adhesive sheet at points diametrically opposed with respect to the above mentioned points of contact, and applying again the coating composition to said cores.

ARMAND JACQUES JULIEN POELMAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 804,034 Perdrizet Nov. 7, 1905 1,012,192 Corkery Dec. 19, 1911 1,225,013 Colt May 8, 1917 1,420,306 Cigol et al. June 20, 1922 1,672,857 Blake et al. June 5, 1928 2,114,999 Fickett et al Apr. 26, 1938 2,285,841 .Sharma June 9, 1942 2,327,299 Yablin Aug. 17, 1943 2,358,651 McGowan Sept. 19, 1944 2,372,755 Abell Apr. 3, 1945 2,407,145 Elwin Sept. 3, 1946 

1. A METHOD OF COATING THE CORES OF IMITATION PEARLS AND THE LIKE WHICH COMPRISES PLACING SAID CORES ON AN IDENTATED PLATE, APPLYING TO THE TOPS OF SAID CORES AN ADHESIVE SHEET MATERIAL APPLYING SLIGHT PRESSURE TO SAID SHEET MATERIAL TO CAUSE SAID CORE LIGHTLY TO ADHERE THERETO, COATING SAID CORES AS FAR AS A PREDETERMINED SMALL AREA SURROUNDING THE POINTS OF CONTACT OF SAID CORES WITH SAID ADHESIVE SHEET, APPLYING ANOTHER ADHESIVE SHEET TO SAID CORES IN DIAMETRICALLY OPPOSED REALTIONSHIP WITH SAID FIRST ADHESIVE SHEET, APPLYING A REALTIVELY STRONGER PRESSURE TO SAID SECOND ADHESIVE SHEET THAN SAID PRESSURE TO SAID SECOND ADTO SAID FIRST ADHESIVE SHEET, STRIPPING SAID SECOND ADHESIVE SHEET WITH SAID CORES ATTACHED THERETO FROM SAID FIRST ADHESIVE SHEET AND COATING SAID CORES AS FAR AS A PREDETERMINED SMALL AREA SURROUNDING THE POINTS OF CONTACT OF SAID CORES WITH SAID SECOND ADHESIVE SHEET. 